Apparatus for molding plastics



July 14, 1942. s. T. MORELAND EIAL APPARATUS FOR MOLDING PLASTICS Filed Sept. 7, 1938 5 Shee'ts-Sheet 1 IN V EN TORS 5. TMOrGLamL m BY VZIHofmann 1 NEYS.

y 1942; s. 'r. MORELAND- ETAL 2,290,129

APPARATUS FOR MOLDING PLASTICS 5 Sheets-Sheet 2 Filed Sept. 7 1938 mmvmas. \%TMore-Zana? "w By E. HOfmanr:

ATYY) S.

y 14, 1942- sl'r. MORELAND arm. 90, 29

APPARATUS FOR MOLDING PLASTICS Fil ed Sept. 'r, 1958 5 Sheets-Sheet s IN V EN TORS. 5. TMoreland w VE.Hofma7rn BY M LTT0$ y 14, 4 s. 1'. MORELAND ETAL 2,290,129

APPARATUS FOR MOLDING PLASTIC S Filed Sept. 7, 1938 5 Sheets-Shee t 4 J w v IN V EN TORS. 5. Tfjlhreland w VE'. Hofmann Arm 5.

Patented July 14, 1942 APPARATUS FOR MOLDING PLASTICS Stephen T. Moreland and Victor E. Hofmann, Toledo, Ohio, assignors to Owens-Illinois Glass Company, a corporation of Ohio Application September 7, 1938, Serial No. 228,732

7 Claims.

The present invention relates to an apparatus for molding synthetic resins, natural resins, and other thermoplastic heat-nonconvertible mate rials which are rigid at normal temperatures but which are capable of deformation under the influence of heat and pressure, these materials being utilized in granular bulk form.

The principal object of the invention is to provide a fully automatic apparatus for molding plastic materials to form hollow shapes such as bottles, jars, and the like, in which charges of the moldable material are formed into parisons or blanks in a blank mold and the parisons or blanks transferred to a finishing mold and expanded to final form therein.

In carrying out the above mentioned object, the invention contemplates the provision of an apparatus and method wherein charges of the granular material are withdrawn from a supply body thereof and are delivered repeatedly to a heating chamber wherein the material isrendered plastic and capable of being molded. Upon delivering each charge to the heating chamber, a portion of the heated material therein is displaced and delivered to a blank or parison mold having associated therewith a series of neck molds which successively move into cooperation therewith and which operate to transfer the parisons successively to a series of finishing molds in which the parisons are expanded by air pressure to final form and from which the articles are discharged as self-supporting articles.

Another object of the invention is to produce hollow blown articles from thermoplastic materials which are transparent and clear and devoid of milkiness and blemishes.

With these and many other objects in View, which will become readily apparent as the nature of the invention is better understood, the same consists in the novel combinations, constructions and arrangements of parts shown in the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional view, with parts thereof in elevation, of a plastic molding machine constructed in accordance with the principles of the present invention;

Fig. 2 is a sectional view taken substantially along the line 2--2 of Fig. 1;

Fig. 3 is a fragmentary detail sectional view illustrating the manner in which the finishing mold table is periodically indexed;

Fig. 4 is an enlarged detail fragmentary longitudinal sectional view taken through a portion of the machine in the vicinity of the blank and neck mold structure;

Fig. 5 is a sectional view taken substantially along the line 5-5 of Fig. 4;

Fig. 6 is a sectional view taken substantially along the line 6-6 of Fig. 4; and

Fig. 7 is a sectional view taken substantially along the line 1-1 of Fig. 1.

Brief description Referring now to Fig. 1, the apparatus briefly involves in its general organization a stationary base l0 including a lower table II and an upper table I2. A charging mechanism I3 delivers measured charges of moldable material from a hopper M to a heating chamber l5 wherein the material is rendered plastic by the application of heat thereto. As each charge of material is delivered to the heating chamber I5, a portion of the plastic material already therein is displaced by the fresh charge and delivered to a blank or parison mold which exists by virtue of a fixed body blank or body parison mold l6 (of which there is only one) with which there is associated, one at a time, a series of neck mold units, each comprising a. partible sectional neck mold I1 and a cooperating plunger l8, said units being supported upon a rotatable carriage l9 which is adapted to be indexed periodically through a predetermined angle. While any number of neck mold units may be utilized in the series, only two have been disclosed, they being arranged in diametrically opposed positions on the carriage and provision being made whereby the carriage is indexed throughout an angle of one hundred and eighty degrees to interchange the positions thereof. Such periodic indexing of the carriage i9 moves the neck molds ll alternately from a mold charging station C, wherein they'coopcrate successively with the body blank mold- I6 in forming a mold cavity, to a forming station F wherein the blanks which are suspended therefrom are enclosed by successive molds 20 of a series of partible sectional finishing molds carried by a rotatable carriage 2|. The blanks or'parisons are expanded against the walls of the finishing molds at the forming station by a blowing operation utilizing the plungers I8 and thus assume the shape of the hollow articles which it is desired to form. After the articles have been fully formed at the forming station, the neck molds are removed and a series of cooling heads 22, of which there is one for each finishing mold, are lowered into operative position and registry with the upper end of their respective molds and function to admit cooling air to the interior of the formed articles to cool and solidify the same. Upon solidification of the articles, the sectional finishing molds open to discharge the articles at a discharging station D (Fig. 2).

The charging mechanism The charging mechanism I3 is best illustrated in Figs. 1, 2, 4 and 7 and comprises a block or casting 23 having an upper surface 30 in sealing contact with the lower end of the body parison mold I6 and provided with an injection aperture 3I normally in register with the mold cavity 32 of the latter. The aperture .3I communicates with the heating chamber I5 formed in the block 23. A series of electrical heating elements 34 encompass the chamber I5 and are adapted to be continuously energized to render plastic the collective charges of moldable material supplied to the latter. The chamber I5 communicates with a cylindrical bore 35 into which there extends the forward end of a reciprocable charging ram 36. The hopper I4 for the moldable material is secured to the block 23 and communicates through an opening 31 with a longitudinal pocket 38. A charge segregating and measuring member 33 slidably disposed in the pocket 33 has formed therein a charge opening 40 which is adapted, upon reciprocation of the member 33, to register with the opening 3! to receive a charge of moldable material therein and transfer the same to a position of register with a slot II which extends between the pocket 38 and bore 35. The charges of material thus moved into register with the slot 4I fall by gravity into the bore 35 immediately ahead of the ram 36 when the latter is in its rearmost position. Upon the charging stroke of the ram, the charge is forced into the heating chamber I5 while at the same time a previously introduced charge is displaced by the fresh charge and is injected into the cavity existing by virtue of the body parison mold I6 and one of the cooperating neck molds IT.

The ram 36 is hydraulically operated by means of a piston 41 which is mounted on the rear end thereof and which is slidably disposed in 8. cylinder 42, the latter being supported upon the table I2. Opposite ends of the cylinder are connected through conduits 23 and 24 to a control valve 43 by means of which fluid is directed alternately to these ends to actuate the piston. Fluid contained in a reservoir 44 provided in the base I is drawn through a stand pipe 45 by means of an oil pump 46 from whence it is directed through a manifold pipe 54 and branch pipe 43 to the valve 43. The valve 43 is provided with a return flow pipe 49. This valve is of the fourway rotor type, the rotor 55 thereof (Fig. 7) being periodically indexed from a shaft 53 which is connected through a gear reduction device I to a motor M. A ratchet type of indexing mechanism I2 is adapted to be periodically actuated by a finger I3 carried by the shaft 53 to index the rotor 55 through an angle of ninety degrees and actuate the charging mechanism in timed relation to the various other phases of machine activity. A relief valve 52 disposed in the manifold pipe 54 directs fluid through a return flow pipe 53 if the pressure developed by the pump 46 becomes excessive. The oil pump 46 is driven continuously by a motor M Referring now to Figs. 1 and 2, a crosshead 56 secured to the ram 36 medially thereof has formed thereon an upstanding finger 51 the uprod 53, one end of the latter being anchored in the charge segregating and measuring member 33. A pair of spaced abutments 59 in the form of nuts threaded on opposite ends of the rod 58 are adapted to be alternately engaged by the finger 51 as the ram approaches the end of its stroke in either direction to move the member 33 alternately in opposite directions and periodically transfer charges of material from the hopper I4 to the bore 35 in the path of movement of the ram 36.

The charge severing mechanism In order that each charge of plastic material injected into the mold cavity 32 shall be severed from the material contained in the heating chamber I5, the casting 29 is capable of limited longitudinal sliding movement in a guide member 63 (Fig. 7) secured to the table I2. The extent of such sliding movement is slight and is barely sumcient to move the injection aperture from its normal position of registry with the mold cavity 32. Toward this end, the crosshead 56 has formed thereon a pair of lateral extensions 6i each provided with an upstanding pin 62. A pair of parallel extending guide rods 63 connecting the cylinder 42 and a crossbar 64 formed on the guide member 63 extend through a pair of ears 65 formed on the casting 23.' A pair of levers 66 are pivoted as at 61 to the ears 65 and are provided with short inwardly extending slots 63 into which a pair of upstanding pins63 provided on the casting 23 extend. The levers 66 are provided with longitudinal slots I3 into which the .pins 62 extend. The rear free ends of the levers 66 are turned inwardly as at II and thus it will be seen that when the ram 36 approaches its rearmost position, the pins 62, riding in the slots I3, cause the free ends of the levers 66 to move outwardly thus shifting the casting 29 and effecting shear of the plastic material in the heating chamber I5.

The plunger and neck mold supporting carriage Referring now to Figs. 1 and 4, the rotatable carriage I3 includes a rotatable central support or column I5 which projects through and is rotatably Journaled in the table portion I2 of the base I3 by means of antifriction bearings I6. A gearII secured to the column I5 meshes with a ring gear I8 associated with the carriage 2I and thus the movements of the two carriages I3 and 2I are synchronized for proper cooperation as will be set forth hereinafter.

A plunger and neck mold supporting head I3 is splined to the column I5 in the upper regions thereof and is movable from a position wherein the plungers I8 and neck 'molds II cooperate with the blank and finishing molds I6 and 23 simultaneously to a raised position wherein these plungers and molds clear the blank and finishing molds. Raising and lowering of the supporting head I3 is accomplished by means of a cylinder 33 supported above the level of the head I3 on a crosspiece 3I (Fig. 7) which in turn is supported on a pair of vertical rods 32 the lower ends of which are threadedly received in the crossbar 34. A piston 33 disposed inthe cylinder is mounted on a rod 34 the lower end of which carries a bifurcated member 35 having a pin and slot connection 36 with the supporting head I3. Thus, it will be seen that upon reciprocation of per end of which is bifurcated and straddles a the piston 33 in the cylinder 33, the head I3 will be lowered and raised to move the neck mold and plunger instrumentalities into and out of operative cooperation with the blank and,b ody molds.

The movements or the piston 83 are controlled by means of a control valve 90 which is similar to the control valve 43 and which is disposed above the reservoir 44 and the rotor of which is driven from the shaft 60. Accordingly, the opposite ends or the cylinder 30 are connected through conduits 9I and 92 to the valve 90.

Cooperation between plunger and neck mold structure and the parison and finishing molds Referring now to Figs. 4 and 7, the body blank mold I6 is supported above the casting 29 by means of tie members 93 secured to the rods 82. The open upper end of the body blank mold I6 is formed with a tapered recess 94 therein and the lower end of the sections 95 of each neck mold I! are correspondingly tapered so that when the sections are closed upon each other and the head is in its lowermost position the tapered portion of either neck mold II will accurately fit into the recess 90 in sealing engagement therewith. The head 19 is formed with a pair of diametrically opposed enlargements 96 from which the plungers I8 are suspended. The sections 95 of the neck molds II are adapted to be closed about the plungers I8 immediately below the enlargements 96. The enlargements are movable upon indexing of the carriage I9 into alignment with the rod 34 with their upper surfaces in engagement with the underneath surface of the member 85. Thus when fluid is admitted to the upper end of the cylinder 80 and the head I9 is in its lowermost position, the closed sections 95 of one neck mold at the charging station C is held in tight sealing engagement with the body blank mold I6 and with the plunger I8 disposed in the mold cavity 32 while the closed sections of the other neck mold at the forming station F are held in sealing engagement with the upper surface of one of the finishing molds 20.

Opening and closing mechanism for the neck molds The sections 95 of each neck mold I! are carried at the outer end of a pair of arms I00, the inner ends of which are pivoted as at IM to the head I9. Opening and closing of the sections upon the plunger I8 is eifected by means of a pair of cylinders I02 (Fig. having pistons I03 therein provided with rods I04 connected by means of links to the arms I00. The outer ends of each pair of cylinders I02 are connected together by a conduit I05 and the inner ends thereof are similarly connected by a conduit I06.

The conduits I05 are each connected through a pipe section I01 to the lower end of a vertically extending groove I08 formed in the head I9. The upper ends of the grooves I08 communicate through horizontal passageways provided in the column I5 with respective vertical bores I09 extending longitudinally through the column.

Similarly, the conduits I06 are each connected through a pipe section IIO to the lower end 01' a vertically extending groove III formed in the head I9. The upper ends of the grooves III communicate through horizontal passageways provided in the column I5 with respective vertical bores II2 formed in the column I5.

The lower portion of the colunm I5, below the table portion I2 of the base I0, has formed thereon an enlarged valve head II3 (Figs. 4 and 6) which is generally of rectangular configuration and which is housed in a chamber Ill provided in the base I0. The lower ends of the bores I09 communicate with respective conduit sections I09 that in turn communicate through passageways I08 leading to respective valve chambers H6 formed inthe valve head H3. The lower ends of the bores II2 communicate with respective conduit sections II2 that in turn communicate through passageways II2 leading to the valve chambers H6. The valve chambers II5 communicate through respective passageways I It with a pressure chamber III formed in the valve head II3. These chambers II5 also communicate through respective passageways I I8 with the atmosphere. The pressure chamber II! is connected to a conduit II9 leading from a source of air under pressure through a bore I20 formed in the lower end of the column 15.

Each valve chamber H6 is cylindrical inform and has mounted therein a rotor I2I adapted to periodically be indexed through an angle of ninety degrees in a manner presently to be described.

Each rotor I2I is provided with passageways I22 and I23 therein which, upon successive indexing operations of the rotor, succeed each other in alternatively connecting the passages I09 and H2 to the passage II6 leading to the pressure chamber Ill and to the passage II8 leading to the atmosphere. In the position of the rotors I2I shown in Fig. 4, wherein one neck mold I1 is closed upon the parison or blank at the charging station C and the other neck mold is closed upon the article undergoing formation at the forming station F, air under pressure is simultaneously transmitted to the outer ends of the cylinders I02 of each pair thereof from the source H9, through the bores I 20, pressure chamber III, passageways II 6, rotors I2I, passageways I09", grooves I08, pipe sections I01, and conduits I05. At the same time the inner ends of the cylinders I02 are vented to atmosphere through the conduits I06, pipe sections IIO, grooves III, vertical bores H2, conduit sections IIZ passageways -II2 rotors I2I, and passageways II8. Upon The article blowing mechanism The pressure chamber III (Fig. 4) communicates through a pair of valves I25 with a pair of vertical bores I26 formed in the column I5. The bores I26 communicate through horizontal passageways I21 with a pair of vertical grooves I28 which are connected by means of pipe sections I29 with passageways I30 formed in the enlargements 96 of the head 1.9. The passageways I30 communicate with bores I3I that extend through the hollow plungers I8. Check valves I32 at the lower ends of the plungers prevent air utilized in the blowing process from being returned through the line from whence it came and also assist in maintaining blowing pressure in the finishing molds 20 after the valves I25 have become closed.

Operating instrumentalities for neck mold opening and closing valves and ,for'the blowing valves e Still referring to Fig. 4. the rotors I2I are mounted on shafts I35 which are iournaled in the valve head III and which carry gears I55 thereon that mesh with racks I31, the latter projecting below the bottom of the valve head. Coil springs I55 normally serve to maintain the racks in their lowermost positionwherein the rotors I2I assume the position shown in Fig. 4.

The valves I25 are provided with stems I2 5 that project below the valve head H3 and are maintained normally in their seated position by means of springs I40.

When either neck mold and plunger assembly is in operative position at the forming station F, the control valves therefor assume a position in the chamber II4 wherein the valve stem I55 and rack I31 are in register with the path of movement of a pair of eccentric cams HI and I42 respectively. The (same I and I42 are mounted on 'a common horizontal shaft I 42 which carries a worm gear I44 by means of which the shaft is driven from a worm I45 connected in a suitable manner to a source of driving power synchronized with the various other phases of machine operation.

The finishing mold carriage Opening and closing mechanism for the finishing molds The sections I54 of each finishing mold have formed thereon an arm I55, the arms being connected to a pair of links I51 which are connected together by means of a pintle I55 carrying a cam roller I59. The various ro1lers-I55 travel in a cam groove I50 provided at the periphery of a stationary cam plate I5I which is secured to and supported from the central column I52. The major portion of the cam groove I50 extending from a point near the forming station F to a point near the discharging station D is circular and the rollers I59 traveling therein operate to maintain the sections I 54 closed upon each other. The groove I50 is formed with an inward bend I52 in the vicinity of the discharging station D into which the rollers I59 ride when the molds arrive at the latter station in order to open the molds and permit the formed articles therein to be discharged. After the articles have been discharged from the molds 20 at the station D. the molds proceed to the forming station F with the sections I54 thereof in an open position and, immediately thereafter when the plunger and neck mold supporting head 15 are lowered to center a parison or blank between the open finishing mold sections I54, means is provided for closing the mold sections I54 about the parison preparatory to commencement of the blowing operation.

Toward this end, the cam plate I5I is provided with a radially shiftable section I63, including a fragment of the cam groove I50, which is consolenoid I55, the latter being mounted on the central column "2. Wires a and b (Figs. 1', 2 and 4) connect the solenoid I55 with a source of energizing current and with a stationary contact I55 designed for intermittent sliding engagement with a movable contactor I51 carried on a disk I55 mounted on the shaft I45. The contactor I51 is connected through a collector ring (not shown) to a wire 0 leading from the source of current. Rotation of the shaft I45 is so synchronized with the various phases of machine operation that the contactor I51 is adapted to intermittently engage the stationary contact I55 when the head 15 is in its lowermost position. when the circuit has been closed. the solenoid I55 is actuated to shift the section I55 of the carn'plate I5I outwardly and thereby move the cam roller I55 outwardly to close the sections I54 of the mold 20 about the parison at the forming station.

When the shiftable section I52 is in its outermost position, it is in alignment with the circular portion of the groove I50. Thus, after the article has been blown to final shape and the carriage 2| is indexed to convey the mold 20 to the discharge station D, the roller I55 will move into this circular portion of the groove I50 and the mold 20 will remain closed until such time as the inward bend I52 is encountered.

Mechanism for applying cooling air to the interior of the finishing molds Referring now to Fig. 1, each cooling head 22 comprises a cup-shape member, the rim of which is designed for sealing engagement with the upper surface of its respective finishing mold 20. The head is formed integrally with an arm I10 which is pivoted for swinging movement in a vertical plane on a short pipe section I1I the latter being supported between a pair of standards I12 carried by the platform I5I. The pipe sections I1I are connected by means of branch conduits I12 with the interior of a hollow rotatable cooling air supply chamber I14 carried at the upper end of the column I52. Each pipe section I" has formed therein a slot I15 adapted to register with a bore I15 formed in the arm I10 when the head 22 is in its lowered position in contact with its respective mold 20. The bore I15 communicates with a hollow nipple I11 adapted to extend into the neck of the article contained within the mold in order that cooling air may be circulated through the article. A vent I15 formed in the side wall of the head 22 permits cooling air to escape to the atmosphere.

Raising and lowering of the heads 22 is effected by means of a stationary cam track I15 which is supported from the column I52 and which provides 'a cam groove I50 into which a series of cam rollers I5I formed on extensions I82 provided on the arms I10 extend. The cam track H5 is so designed that the heads 22 become raised immediately prior to arrival of the molds at the discharge station D and remain raised until the sections I 54 of the molds are closed upon the parison at the forming station F and the molds have commenced to move toward the discharge station,

Indexing mechanism for the finishing mold a carriage Referring now to Figs. 1, 2 and 3, periodic indexing of the finishing mold carriage 2i through an angle of sixty degrees is effected by means nected by .a link I54 to the movable core of a of a circular rack I50 secured to the underneath side of the platform II. The rack I90 is provided with ratchet teeth I9| which are adapted to be engaged by a spring pressed pawl I92 carried at the outer end of a plunger I93 connected to a piston I94 disposed in a cylinder I95 pivoted as at I96 to a bracket I91 formed on the upper table portion I2 of the base l0. The outer end of the plunger I93 is guided by means of a horizontal rock arm 205 pivoted to oscillate about the axis of the column I52 and thus engagement between the pawl I92 and'rack I90 is always insured. Conduits I98 and I99 connect opposite ends of the cylinder I95 to an actuating valve 200 which is identical with the actuating valves 43 and 90 and which is similarly periodically indexed from the common shaft 50 in timed relation to the various other phases of machine operation.

The stroke of the piston I94 is of a magnitude sufliclent to impart rotary movement to the carriage 2| at each stroke thereof through an angle of sixty degrees. A hollow boss 20I (Fig. 1) formed on the stationary cam plate I6I provides a mounting for a spring pressed holding dog 202 which is adapted to enter a depression 203 (of which there are six) formed in the platform I5I after each successive indexing operation to insure accuracy of alignment of the neck molds and finishing molds at the forming station F,

Cooling of the finishing molds Upon each indexing movement of the carriage 2| the various molds 20 are advanced through an angle of sixty degrees in the direction indicated by the arrow in Fig. 2. A series of blow pipes 204 (Fig. 2) positioned about the periphery of the carriage 2I and spaced apart sixty degrees with respect to the axis of the carriage serve to direct cooling air against the molds 20 during the interval between indexing operations. These pipes 204 are adapted to direct air inwardly of the carriage 2I continuously. Where the articles undergoing formation are transparent in the final product, experience has shown that it is essential to maintain the temperature of the finishing molds at the forming station F at substantially room temperatures or at least not above 110 F. if articles which are clear and de void of milkiness and air bubbles are to be produced. Accordingly the cooling air which is directed against the finishing molds in addition to cooling the enclosed articles therein also conditions the molds for the next succeeding forming operations.

Operation of .the apparatus In actual operation, the hopper I4 (Fig. 1) is maintained supplied with the solid granular thermoplastic material from which measured charges thereof are periodically segregated and transferred to the cylindrical bore 35. Reciprocation of the charging ram 36 forces these charges into the heating chamber I5 wherein they displace a quantity of the material that has previously been rendered plastic by virtue of the heat supplied by the heating elements 34. The displaced material is injected through the aperture 3| into the mold cavity 32 existing by virtue of the fixed body blank mold I6 and the cooperating plunger I8 and neck mold I 1.

Immediately thereafter, and while the ram 36 is retracted preparatory to its next succeeding charging stroke, the control valve 90 is actuated to elevate the piston 83 and raise the head 19 and thus withdraw the parison from the mold I6, the parison being suspended from the neck mold I1.

Following the elevation of the head 19, the control valve 200 is actuated and, through the medium of the piston I94 (Fig. 2), the finishing mold carriage is indexed through an angle of sixty degrees. Motion of the carriage 2I is transmitted to the carriage I9 by virtue of the gears 11 and 18 and the latter carriage is indexed through an angle of one hundred eighty degrees, thus interchanging the positions of the neck molds I1. The parison suspended from the neck mold at the charging station C is transferred to the forming station F and is suspended above the open sections I54 of one of the finishing molds 20 which has moved into position at this latter station.

Immediately after the indexing operation, the control valve is actuated to lower the head 19 and, when the head approaches its lowermost position, the contactor I61 (Fig. 4) engages the stationary contactllifi and the circuit through the solenoid I65 (Fig. 2) is closed Upon energization of the solenoid I65, the movable section I63 of the cam plate I6I is moved outwardly and the sections I54 of the finishing mold at the forming station F are closed upon the parison which has been lowered into position between the mold halves.

After the finishing mold sections become closed, one of the valves I25 (Fig. 4) is elevated from its seat by the cam I42 and blowing air is applied to the interior of the finishing mold to expand the parison to its final shape.

Prior to the next indexing operation of the mold carriage 2I', one of the valve rotors I2I is actuated by the cam I42 andthe pistons I03 (Fig. 5) are moved in such a manner as to cause the sections 95 of the neck mold I1 to open and release the neck of the formed article.

Upon such release of the article by the sections of the neck mold,-the head 19 is elevated in the manner previously described so that the 'neck mold will clear the finishing mold when the carriage 2I is next indexed and the molds move away from the forming station F.

After the head 19 is elevated the mold carriage 2I is again indexed and during movement of the finishing mold 20 away from the forming station, the cooling head 22 is lowered into cooperating engagement with the mold 20. As the cooling head 22 comes into engagement with the mold 20, the bore I16 comes into register with the slot I15 and cooling air is circulated in the relatively soft formed article.

During the next several indexing operations of the mold carriage 2|, the finishing mold with the formed article contained therein is moved successively through a series of sixty degree angles and during each pause of th carriage 2|, cooling air issuing continuously from the blow pipes 204 impinges against the outside of the mold 20 to further cool the same by convection.

As the mold approaches the discharge station 7 D, th roller I59, entering the inward bend I62 provided in the cam groove I60, causes the mold carrier comprising a plunger and a neck mold surrounding the plunger and defining therewith an annular neck mold cavity, means for moving ishing molds thereon, means for rotating the carriage intermittently step by step and thereby bringing the finishing molds in succession to a transfer station, means for rotating the neck mold carrier step by step in synchronism with the rotation of said carriage and thereby moving the neck mold alternately from a charge-receiving station to said transfer station, and means for transferring parisons from the neck mold to the finishing molds at said transfer station.

2. A machine for forming hollow articles. comprising a parison mold, a neck mold carrier mounted for rotation about a vertical axis, neck mold units on said carrier at opposit sides of said axis, each said unit comprising a plunger and a neck mold surrounding the plunger and defining therewith an annular neck mold cavity, means for rotating said carrier and thereby bringing said units alternately to a position directly over the parison mold, means for lowering and lifting said carrier and thereby lowering and lifting each neck mold unit into and out of a position in which the neck mold and parison mold are juxtaposed and the plunger projectsinto the parison mold, means for injecting charges of plastic material into the molds while in said juxtaposed position and thereby forming parisons therein, finishing molds, and means for transferring parisons from each neck mold unit to a finishing mold while the other neck mold unit is in juxtaposition to the parison mold.

3. A machine for forming hollow articles from plastic material, comprising a parison mold open at top and bottom, a neck mold carrier mounted for rotation about a vertical axis and for up and down movement, neck molds mounted on said carrier at opposite sides of said axis, plunger on said carrier and projecting downwardly through the neck molds, means for rotating the carrier intermittently and thereby bringing the neck molds alternately to a position over the parison mold, means for lowering the carrier and thereby bringing a neck mold into juxtaposition with the parison mold and projecting the associated plunger downward into th parison mold, means for forcing a charge of th plastic material through the lower end of the parison mold while a plunger is in said projected position therein and thereby forming a parison in the juxtaposed molds, finishing molds, and means for transferring each parison from a neck mold into a finishing mold while the other neck mold is over the parison mold.

4. An apparatus for forming hollow articles from synthetic resins, comprising a stationary body parison mold, a movable finishing mold, a neck mold unit comprising a plunger projecting into the parison mold through one end thereof and a neck mold surrounding the plunger and closing said end of the parison mold, automatic means for injecting a charge of plastic material into the parison mold through the other end thereof while the plunger and neck mold are in said position, automatic means operable thereafter to withdraw-said neck mold unit from the 76 parison mold with the charge of plastic material and move it into a position of cooperation with the finishing mold wherein the plunger is projected into the finishing mold cavity, and means for blowing the parison to final shape within the finishing mold.

5.. In an apparatus for forming hollow articles from thermoplastic materials, the combination of a parison forming mechanism including a single body parison mold and a plurality of cooperating neck mold units, each neck mold unit comprising a plunger and a neck mold surrounding the plunger, automatic means for moving said neck mold units in succession into a position in which the neck mold unit closes one end of said parison mold and the plunger projects into the mold, automatic means for introducing charges into plastic material into the parison mold while a neck mold unit is in said position, a plurality of partible finishing molds, transfer instrumentalities for moving the neck mold units out of cooperation with the body parison mold and into cooperatibn with the finishing molds, said instrumentalities including means for elevating the neck mold units and thereby withdrawing a said unit from the body parison mold with the parison surrounding the plunger and suspended from the neck mold and for lowering the neck mold units and thereby lowering the suspended parison into a position of registry with a finishing mold, means for closing the finishing molds about the suspended parisons, and automatic means for synchronizing the operation of the transfer instrumentalities and the movements of the finishing molds.

6. In an apparatus for forming hollow articles from thermoplastic materials, a parison forming mechanism including a single stationary body parison mold positioned at a charging station, a series of partible finishing molds, means for moving the finishing molds from a forming station to a discharging station, a pair of neck mold units, each comprising a plunger and a neck mold surrounding the plunger, means for moving each said unit from a position of cooperation with the body parison mold at the charging station,

with the plunger projecting into the parison mold and the neck mold and plunger closing the end of the parison mold, to a position of cooperation with the finishing molds at the forming station, in which last mentioned position the finishing molds and neck mold units together provide mold cavities of the shape of the finished articles, means for injecting charges of plastic material into the-parison mold cavities at the charging station while the neck molds and plungers are in said cooperative position, means for movin 'the neck mold units to transfer the pafisons from the body parison mold to the finishing molds while the parisons surround the plungers and are suspended from the neck molds, means for closing the finishing molds about the parisons at the forming station, means for blowing the parisons within the finishing molds, means for thereafter withdrawing the neck molds and plungers, and means for opening the finishing molds at the discharging station.

7. In an apparatus for forming hollow shapes from thermoplastic materials, a stationary, openended, parison mold positioned at a charging station, a rotary carriage, an annular series of finishing molds thereon, means for periodically indexing said carriage and thereby moving the finishingmolds past forming and discharge stations, a second carriage, diametrically opposed neck mold units thereon, each comprising a neck mold and a plunger, means cooperating with said second carriage for moving one neck mold unit into position to close an open end of the parison mold and cooperate with the parison mold to form a parison mold cavity and simultaneously move the other neck mold unit into position to cooperate with a finishing mold at the forming station to form a mold cavity for the finished article, and vice versa, means for injecting 10 charges of plastic material into successively 

